The mentioned operators are not the same "sort" of operators as those listed in 
the operator precedence table. It would not provide any benefit to list them 
there, as they have ultimate precedence in any statement, and no combination of 
them is both valid and ambiguous.

I feel that it's actually important to know whether :: or -> has higher precedence. consider:

\Namespace::$static_public_object->public_method();

Am I resolving the namespace first on $object or am I looking for a $object in the current context and attempt to call it's method() first?

or what about a static method in the above example?

\Namespace::$static_public_object::static_public_method();

which scope gets resolved first?

Even though the "incorrect" interpretation would probably result in parser errors, there would be no harm in clarifying this for users.